As investigators piece together shreds of information and evidence on the blasts in Hyderabad, one of the few workable clues being looked at is the trigger mechanism which is learnt to be similar to the one used in the Sankat Mochan blasts in Varanasi. And thin as it may seem, one of the key lines of investigation that the Hyderabad police are chasing is a possible linkage between a spate of recent seizures of counterfeit currency, alleged to be the handiwork of the Pakistan ISI, and the perpetrators of the blasts.

On the day the serial blasts occurred in Hyderabad, the city police had announced its biggest catch in counterfeit currency — Rs 2.36 crore from four persons allegedly associated with the ISI and Dawood Ibrahim. Hyderabad police commissioner Balwinder Singh said today that his investigators were probing all angles. “The angle of a link between the blasts and the fake currency is also being examined,” he said.

Meanwhile, what has got investigators interested is the timer and trigger mechanism used in the Varanasi and Hyderabad blasts.

Initial investigations, sources said, shows that the same type of quartz watch timer was used. An alarm is set in the watch and when it rings, the circuit is completed leading to an explosion. These are small alarm clocks with 9 volt batteries connected to a detonator.

In both cases, the perpetrators have relied on locally available material to make a simple but effective circuit and have used a set of two detonators. This, sources said, is done to ensure a back-up in case one of the detonators were to fail.

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